Blade assembly for drum dryers or the like



June 26, 1962 s. OVERTON 3,040,442

BLADE ASSEMBLY FOR DRUM DRYERS OR THE LIKE Filed April 27, 1959 2 SheetsSheet 1 Ly/e 5. fll erfazz b 4 1 272 75 June 26, 1962 s. OVERTON 3,040,442

BLADE ASSEMBLY FOR DRUM DRYERS OR THE LIKE Filed April 27, 1959 2 Sheets-Sheet 2 hem 1151/6 5 017617 011 United States Patent 3,040,442 BLADE ASSEMBLY FOR DRUM DRYERS 0R THE LIKE Lyle S. Overton, 404 Center St, Dowagiac, Mich.

File-d Apr. 27, 1959, Ser. No. 809,308 11 Claims. (Cl. 34-410) This invention relates to a drum dryer for food products and the like, and more particularly to a drum dryer having a floating doctor knife or scraper blade for removing dehydrated material from the dryer which is mounted on the dryer between a pair of independently adjustable plates for maintaining the blade in a desired pressure relationship with the drum.

Heretofore, the doctor blade for a dryer drum has been firmly attached to a supporting plate mounted on the dryer, either by bolts or the like or by pinching it between a pair of opposed bolted together plates. These constructions have produced anuneven blade pressure with a consequent incomplete scraping action. The present invention provides for an even scraping pressure across the entire face of the dryer drum, and also prevents buckling of the blade when the blade expands from heat transmitted by the drum. The blade is positioned in a sandwich type of construction between a pair of plates received in a' doctor bar housing on the dryer in independently adjustable relationship, one of the plates having a backing shoulder engaging the blade. Although the blade can slide between these plates, the backing shoulder maintains a desired blade pressure on the drum. The other plate is adjustable so that its leading edge is spaced from the active edge of the blade so as to aliord various desired pressure point locations for the edge of the blade.

In one embodiment of the invention, pressure fingers are pivotally mounted on the housing for the doctor bar and these fingers are urged against the blade by means of an air inflated hose to accommodate the various desired pressure point locations for the active edge of the blade.

The doctor bar may be relocated and the blade angle varied by means of a journal plate which may also pivotally support the drum in adjustable relation to another drum in the dryer. Adjustment of the plates of the doctor bar assembly of the invention is accomplished by bolt means in which one bolt is threadedly engaged in one of the plates and with a nut or the like on top of the housing to afford relative positioning of the plate in the housing. The other of the plates may be moved by a bolt threadedly received in the housing whose end engages the plate for actuating the same axially toward the drum by means of the aforementioned backing shoulder thereof.

Accordingly, it is an object of the present invention to provide a drum dryer as described having a doctor bar assembly wherein the blade is provided with a floating mount so that even scraping pressure across the entire face of the dryer drum is assured.

Another object of the invention is to provide a dryer assembly in which support means for the doctor bar assembly cooperate in affording pivotal support for the drum therefor to permit adjustment between the drum and another drum of the dryer.

Another object of the invention is to provide a doctor blade assembly as described wherein the mounting for the scraper blade prevents buckling of the blade under expanded conditions such as occur when the blade is heated by the drum.

Another object of the invention is to provide a doctor blade as described wherein a cover plate is adjustably mounted by bolt means ina housing for the doctor bar 3,049,442 Patented June 26, 1982 assembly so that the plate has its leading edge positioned relative to the edge of the blade to accommodate various desired pressure point locations for the active edge of the blade.

Another object of the invention is to provide a doctor bar assembly for a dryer drum as described wherein the blade is disposed between the aforementioned cover plate and an independently adjustable plate equipped with a backing shoulder for maintaining the desired blade pressure on the drum.

Another object of the invention is to provide a dryer drum assembly as described in one embodiment of which pressure fingers are pivotal-1y mounted on the doctor bar housing and a pneumatic hose bears against an upper portion of the fingers so that the lower ends of the fingers engage the blade and accommodate the various desired ressure point locations for the blade.

Other objects and advantages of the invention will become apparent as the description proceeds in accordance with the drawings in which:

FIGURE 1 is a perspective view of the dryer drum assembly according to the present invention;

FIGURE 2 is a vertical sectional enlarged and fragmentary view of a doctor bar assembly according to the invention;

FIGURE 3 is aview corresponding to the view of FIGURE 2 showing the doctor bar assembly in a different position relative to the drum;

FIGURE 4 is a view corresponding to the views of FIGURES 2 and 3 but showing another embodiment of the doctor bar assembly of the invention including pneumatically actuated finger means for adjusting the pressure position of the doctor bar blade;

FIGURE 5 is a view corresponding to the views of FIGURES 2-4 and representing another embodiment of the invention;

FIGURE 6 is an enlarged fragmentary view showing the relationship of blade positioning fingers shown in FIGURE 5; and

FIGURE 7 is a side elevational view, partly broken away, of the dryer assembly of the invention and showing adjustable support means for the doctor bar and the drum associated therewith.

Referring now to the drawings, a dryer drum assembly 10 is shown according to the invention which is adapted for a wide range of applications and which may be changed quickly from one type of drying to any other or adapted for flaking or chilling. A table 12 is provided for supporting the drums in the housing 14 thereof and a doctor bar assembly 16 is adjustably mounted on the assembly 10 as hereinafter set forth. Suitable tanks 18 and 20 for receiving processed material may also be provided as understood by those skilled in the art. The dryer may be heated by steam or by direct gas heating and various types of heat control devices and controls for liquids or slurries are provided (not shown), as will be understood by those skilled in the art. The housing 14 is preferably a onepiece vacuum housing with all of the controls on the outside thereof for continuous dry product evacuation. The assembly .10 may be easily adapted to dip or splash feed, and used with mechanical and pneumatic conveying and milling equipment. Special ducts (not shown) are preferably provided to remove vapors from under the drums and gauges and indicators may also be provided for indicating drum spacing, end dam location and blade pressure. The drums 19 and 21 may be of cast iron, steel, chromium plate or bronze material, as desired.

Referring now to FIGURES 1 and 2, the doctor bar assembly 16 is supported on a pair of arms 22, and 24, as hereinafter further described, and includes a blade housing 26. The housing 26 defines an elongated recess 28 of substantially rectangular cross-sectional configuration, in which are slidably received a blade extension slide or plate 30 and a set screw slide or cover plate 32. A blade 34 is received between the blade extension plate 30 and the cover plate 32 in a sandwich construction, and in order to afford a desired blade pressure on the drum, the blade extension plate 30 is provided with a backing shoulder 36, which engages the upper end of the blade, as shown. The plates 30 and 32 may be of stainless steel clad construc tion, bronze or any other suitable material.

In order to provide for variable blade angles and pressure points, a plurality of bolts 38 is threadedly received in the housing 26 for engagement at their lowermost ends with the upper surface of the blade extension plate 30. A corresponding plurality of bolts 40 is provided adjacent the bolts 38 and extends into threaded engagement within the plate 32. A nut 42 is provided for each of the bolts 40, at the upper surface of housing 26, so that upon rotation thereof, manually or otherwise, the plate 32 will be adjusted selectively upwardly as afforded by a suitable adjustment as the nuts 42. Appropriate threaded adjustment of the bolts 38 in the housing 26 will move the plate 32 downwardly within the recess 28. In order to urge the blade 34 against the drum 21 with a desired amount of pressure, a set screw 44 is adjustably received in the plate 32 to direct a force substantially perpendicular thereto, it being understood that similar doctor bar assembly means are provided for drum 19.

Upon loosening the screws 44, the blade extension plate 32 may be moved selectively downwardly by means of the bolts 40, and adjustment of the nuts 42, to position by gravity or otherwise, the leading edge "48 of the plate 32 in a desired spaced relation to the active edge 50 of the blade 34 so as to accommodate various pressure point locations for the edge 50 in accordance with means for adjusting the angle of the assembly 16 hereinafter referred to. The blade 34 is shown in FIG. 2 at a blade angle of approximately 30, which represents a maximum value in the embodiment shown. In order to retain the blade in position between the plates 30 and 32 during adjustment thereof, a blade retaining means 31 is provided which includes an elongated rod 33 secured in depending relation to the housing 26 and having an outwardly extending member 35 threadedly engaging the rod. The member 35 underlies the blade for releasable engagement therewith, and it will be understood that the rod 33 could also be moved relative to the housing 26 to adjust the member 35 directly rather than by means of the nuts 35a on which the member 35 may be journalled.

Referring now to FIGURE 3, a (preferred) minimum blade angle relative to the drum of approximately is shown in a construction substantially of the type indicated in FIGURE 2. This angle eliminates blade and drum wear and is especially suitable in that very light blade pressure will remove dried products from the drum 21.

Referring now to FIGURE 4, another embodiment of the invention is shown wherein a blade 52 is provided which is of a light, relatively thin and flexible construction such as to strip the dried product from the drum. The blade 52 is self-sharpening and, therefore, must have a uniform pressure applied near the edge 53 thereof.

In order to produce such a uniform pressure, a pneumatic assembly 54 is provided comprising an air hose 56 received in a saddle-shaped groove 58 in the housing 14, and secured thereto by any suitable means (not shown). The hose 56 is closed at one end and is fed compressed air through the other end thereof. Desirably, it is given an amount of pressure initially such that it is partially flat, so that as air pressure is increased, the hose 58 will tend to become increasingly round. A plurality of fingers 60 are positioned with their upper ends against the hose 56, as held by a plurality of adjusting screws 62 threadedly received in the lower portion of the housing 16 for inward and outward adjustment relative thereto so that the lower ends 64 of the fingers 60 engage the lower portion of the blade 52 near its active edge 53. One form of construction for these screws 62 may be seen in FIGURE 6, although other forms of set screw construction may be used as desired. The fingers 60 may, for example, be /2 wide, and pivot rods or trunnions 66 and 68 extend from either side of the screws 62 to provide a pivot point for the fingers. Thus the trunnions 66 and 68 serve as fulcrum points, with expansion of the hose 58 tending to rotate the fingers 60 clockwise thereabout to afford pressure at the ends 64 of the finger engaging the lower portion of the blade 52. It will be understood, however, that a direct pivotal connection may be afforded intermediate the ends of the fingers, and that the fingers are illustrated in FIG- URE 6 With the spacing therebetween somewhat exaggerated, since the spacing will be preferably such as to afford a side-by-side relationship for the fingers to maintain a continuous relationship with the blade 52. The rockers or fingers 60 may thus be adjusted so that an even, light pressure is applied near the blade edge 53. As air pressure is increased in the hose 56, and the hose becomes correspondingly round, the greatest expansion of the hose will occur at the points of least resistance as determined by the fingers 60, i.e., at locations corresponding to blade areas where the blade pressure on the drum is relatively low. The fingers 60 will thereby exert a relatively greater force on such blade areas, and thus the pressure or force with which the blade 52 engages the drum 21 will be sensitively and automatically equalized along the full length of the blade edge 53. Also, since the blade is not clamped rigidly but is allowed to expand as it is heated from contact with the drums, unevenness at the edge, such as has characterized previously available constructions, is eliminated.

Referring now to FIGURE 5, still another form of the invention is shown wherein a blade 70 of preferably medium thickness is used in conjunction with the pneumatic assembly described. In this embodiment, a saddle structure 72 is secured to the fingers 60, preferably by means such as screws 74 in position to engage the hose 56 as shown. Thus the fingers 60 are maintained in a desired predetermined relation to the hose means and the blade. Adjustment of the pressure or force with which the blade engages the drum is advantageously accomplished by means of the screw elements 62 rather than by means of the set screws 44, since adjustment of the force acting perpendicularly on the lower portions of the blade may thereby be made without loosening substantially the engagement of the blade with the plates. A plurality of apertures 75 are formed in each of the fingers 60 to threadedly reeeive the individual screws 74 and afford adjustment of the blade pressure as desired by variation in the point of contact of the fingers with the blade.

Referring now to FIGURE 7, means for cooperatively supporting the doctor bar assembly 16 and the drum 21 are shown including a plate 76 in which the drum 21 is journalled, and having an arm 78 provided with a shaft or trunnion 80 rotatably received in a heavy base plate 82. The arms 22 for holding the doctor bar assembly 16 are adjustably positioned on the plate 76 by suitable screws or the like 84 removably received in spaced apertures 86 in the plate 76. Thus, the doctor bar assembly may be varied from higher to lower as desired, and also in accordance with the relative position of the plate 76, which may be pivotally adjusted by means of a wheel 88 threadedly mounted on a shaft 90 on the base plate 82. An extension 92 of the plate 76 slidably engages a reduced portion 94 of the wheel 88 for this purpose. The doctor bar assembly 16 may be adjusted as hereinbefore described, as well as by manually operable Wheels 96 threadedly received in fixed brackets 98, in bearing engagement with carrier arms 100 pivotally mounted on the arms 22, so that the setting of the dotcor bar assembly may be varied to accommodate changes resulting from adjustment of the drums relative to each other, or from changes in the angular position of the arms 22. i

It will thus be seen that I have provided a floating mount for a doctor bar blade which affords uniform pressure engagement of the blade with a dryer drum throughout a wide range of angular adjustment, as well as means to vary the pressure engagement which permit easy adjustment of the blade angle. The doctor bar assembly of the invention may also be positioned in a desired relationship with the drum with the blade adjustment means of the assembly cooperating With the means for adjusting the position of the assembly, as well as the position of the drum, to maintain a maximum effectiveness at all times. Because the floating mount accommodates variations in blade length due to changes in thermal conditions in the drum and in the blade, the device eliminates unevennesses in scraping action which have occurred heretofore, and the means for pneumatically ensuring a desired blade pressure over the length of the blade cooperate with the floating mount for the blade to produce a degree of effectiveness which renders the blade assembly suitable for a virtually unlimited variety of operations.

Although I have herein set forth and described my invention with respect to certain specific principles and details thereof, it will be understood by those skilled in the art that these may be varied Without departing from the spirit and scope of my invention as set forth in the hereunto appended claims.

I claim as my invention:

1. In combination with a rotating drum type dryer, a doctor bar assembly comprising a housing mounted on the dryer to extend across the length of the dryer drum thereof, said housing having a blade-receiving recess longitudinally thereof and opening towards said drum, first and second plates received in said recess in mating engagement therewith and extending longitudinally thereof while being slidable'trasversely thereof through said opening, a backing shoulder extending longitudinally of said first plate on a side thereof disposed transversely away from said drum, a doctor blade extending longitudinally in said recess between said plates and transversely outwardly through said opening, means for moving said first plate transversely in the direction of said opening and toward said drum, said shoulder engaging said blade to effect movement of said blade toward said drum, and means for moving said second plate transversely toward or away from said opening and toward or away from said drum and cooperating with said first plate to place said blade in a desired relationship to said drum.

2. In combination with a rotating drum type dryer, a doctor bar assembly comprising a housing mounted on the dryer to extend across the length of the dryer drum thereof, said housing having ablade-receiving recess longitudinally thereof and opening towards said drum, first and second plates received in said recess in mating engagement therewith and extending longitudinally thereof while being slidable transversely thereof through said opening, a backing shoulder extending longitudinally of said first plate on a side thereof disposed transversely away from said drum, a doctor blade extending longitudinally in said recess between said plates and transversely outwardly through said opening, means for moving said first plate transversely in the direction of said opening and toward said drum, said shoulder engaging said blade to effect movement of said blade toward said drum, and means for moving said second plate transversely toward or away from said opening and toward or away from said drum and cooperating with said first plate to place said blade in a desired relationship to said drum, said second plate carrying means outwardly of said recess for maintaining said blade in adjustable pressure engagement with said drum.

3. In a drying apparatus havinga rotatable drum, a doctor bar assembly which includes a housing mounted on the dryer to extend across the length of the drum, said housing having a recess extending longitudinally thereof and opening toward said drum, first and second plates slidably received in and mating with said'recess, said first plate defining a backing shoulder extending longitudinally thereof in transversely spaced relationship to the longitudinal edge thereof closer to said drum, a blade received between said plates in abutting engagement therewith and with said backing shoulder, said blade extending from said recess toward said drum and defining a scraper knife edge engaging the drum, bolt means threadedly re ceived in said housing and extending in abutting engagement with said first plate toalford adjustment of said first plate away from said bolt means, bolt means freely received in said housing and in threaded engagement with said second plate and means for adjusting the position of said freely received bolt means relative to said housing to afford adjustment of the position of said second plate in said housing.

4. In a drying apparatus having a rotatable drum, a doctor bar assembly which includes a housing mounted on the dryer to extend across the length of the drum, said housing having a recess extending longitudinally thereof and opening toward said drum, first and second plates slidably received in and mating with said recess, said first plate defining a backing shoulder extending longitudinally thereof in transversely spaced relationship to the longitudinal edge thereof closer to said drum, a blade received between said plates in abutting engagement therewith and with said backing shoulder, said blade extending from said recess toward said drum and defining a scraper knife edge engaging the drum, bolt means threadedly received in said housing and extending in abutting engagement with said one plate to afford adjustment of said plate away from said bolt means, bolt means freely received in said housing and in threaded engagement with said second plate, means for adjusting the position of said freely received bolt means relative to said housing to afford adjustment of the position of said second plate in said housing, and means carried by said second plate outwardly of said recess for adjustably effecting a desired blade pressure relative to said drum.

5. In combination with a drying apparatus having a rotatable drum, a doctor bar assembly comprising a housing extending across the length of the drum and having a longitudinally extending blade-receiving recess, a blade seated in said recess and extending therefrom toward the drum to provide a scraper blade edge engaging the drum, inflatable means on said housing, a member extending from said inflatable means to a location on said blade adjacent to said tip and means pivotally supporting said member for pivotal movement about a predetermined axis intermediate its ends to transmit pressure from said inflatable means to said blade.

6. In combination with a drying apparatus having a rotatable drum, a doctor bar assembly comprising a housing having a recess extending along the length of the drum and opening toward the drum, first and second plates slidably received in said recess in mating engagement therewith, bolt means threadedly received in said housing and disposed in abutting engagement with said first plate at a longitudinal edge within said recess, bolt means freely received in said housing and extending into threaded engagement with said second plate through a longitudinal edge within said recess, means for adjusting the position of the second named bolt means relative to said housing and thereby adjusting the position of said second plate in said housing, a blade disposed between said plates in abutting engagement therewith, shoulder means on said first plate engaging a longitudinal edge of said blade within said recess, said blade extending transversely outwardly from said recess and having a longitudinal edge outwardly of said recess forming a tip for engagihg said drum in pressure relationship, pneumatic means on said housing, finger means engaging said pneumatic means and engaging said blade between said recess and said drum, and pivot means engaging said finger means between said pneumatic means and said blade to afford pivotal movement of said finger means and transmission of pressure from said pneumatic means to said blade.

7. In combination with a drying apparatus having a rotatable drum, a doctor bar assembly comprising a housing having a recess extending along the length of the drum and opening toward the drum, first and second plates slid-ably received in said recess in mating engagement therewith, bolt means threadedly received in said housing and disposed in abutting engagement with said first plate at a longitudinal edge within said recess, bolt means freely received in said housing and extending into threaded engagement with said second plate through a longitudinal edge within said recess, means for adjusting the position of the second named bolt means relative to said housing and thereby adjusting the position of said second plate in said housing, a blade disposed between said plates in abutting engagement therewith, shoulder means on said first plate engaging a longtudinal edge of said blade within said recess, said blade extending transversely outwardly from said recess and having a longitudinal edge outwardly of said recess forming a tip for engaging said drum in pressure relationship, pneumatic means on said housing, finger means engaging said pneumatic means and engaging said blade between said recess and said drum, pivot means engaging said finger means between said pneumatic means and said blade to afford pivotal movement of said finger means and transmission of pressure from said pneumatic means to said blade, and means carried by said second plate outside of said recess for adjustably engaging said blade to urge said blade against said drum.

8. A drum drying assembly comprising -a pair of rotatable drums, a base, a pair of support members for each of said drums, said support members being pivotally mounted on said base, means for adjusting the angular position of each of said support members, said support members each defining a plurality of angularly spaced apertures, an arm for each of said support members, means connecting said arms to the support member associated therewith to maintain the arms in angularly adjustable position on said support members, and a doctor bar assembly for each of said drums carried by the arms of the support members therefor, each of said doctor bar assemblies including a housing extending for the length of the drum thereof and defining a longitudinal recess, a blade seated in said recess and having a longitudinal tip engaging said drum outside of said recess and means for adjusting the transverse position of said blade relative to said housing.

9. In combination with a drying apparatus having a rotatable drum, a doctor bar assembly comprising a housing extending for the length of said drum and defining a longitudinal recess, a blade seated in said recess, means in said housing for maintaining said blade in contact with said drum along a longitudinal edge of said blade outside said recess, pneumatic means extending longitudinally along the outside of said housing, a plurality of elongated fingers each having an end contacting said pneumatic means in overlying relation thereto and an end pressingly contacting said blade, and a plurality of screw elements threadedly received in said housing each carrying rod elements overlying adjacent fingers intermediate the ends of said fingers with the rod elements disposed transversely to the fingers to retain said fingers in adjustable, pivotal contact with said pneumatic means and said blade between said housing and said drum, said pneumatic means being inflatable to a variable extent whereby to efiect a desired pressure engagement of said blade with said drum.

10. In combination with a drying apparatus having a rotatable drum, a doctor bar assembly comprising a housing extending for the length of said drum and defining a longitudinal recess, a blade seated in said recess, means in said housing for maintaining said blade in contact with said drum along a longitudinal edge of said blade outside said recess, a hose on said housing closed at one end and having an inlet at the other end for receiving fluid under pressure, a plurality of elongated fingers each having one end overlying said hose and another end contacting said blade, and a plurality of screw elements thereadedly received in said housing each carrying rod elements overlying adjacent fingers to retain said fingers intermediate the ends of said fingers and transversely of said fingers, in adjustable, pivotal contact with said hose and said blade between said housing and said drum, said hose being inflatable to a variable extent whereby to eflect a desired pressure engagement of said fingers with said blade and thereby of said blade with said drum.

11. In combination with a drying apparatus having a rotatable drum, a doctor bar assembly Comprising a housing extending for the length of said drum and defining a longitudinal recess, a blade seated in said recess, means in said housing for maintaining said blade in contact with said drum along a longitudinal edge of said blade outside said recess, a hose on said housing closed at one end and having an inlet at the other end for receiving fluid under pressure, a plurality of elongated fingers, means connecting said fingers to said hose in overlying relationship thereto, at one end of said fingers, and pivot means retaining said fingers in contact with said blade, said hose being adjustably inflatable to pivotally adjust the fingers and thereby adjust the pressure of said fingers on said blade and the pressure of said blade on said drum, said fingers being independently loaded to equalize blade pressure against the drive drum along the entire length of the blade. 1

References Cited in the file of this patent UNITED STATES PATENTS 488,455 Scallen Dec. 20, 1892 767,933 Galleciez Aug. 16, 1904 1,566,358 White Dec. 22, 1925 1,927,694 Wood Sept. 19, 1933 2,273,021 Cox Feb. 17, 1942 2,330,889 Holcomb Oct. 5, 1943 2,477,339 Ljungquist July 26, 1949 2,678,093 Fischer May 11, 1954 

